AMD had their own quad-core laptops available for a long time too, the Excavator/Piledriver series goes back many years as well.
Cheap dual-cores have been around forever as well, this is not something that AMD has brought on with Zen. This is not really a distinctive product in most ways, it's just a replacement for those old cheapo Excavator products for bargain-basement laptops. So I'm not sure what you're trying to say here other than 'AMD good'.
dual-cores have always been the standard for ultrabooks, but those laptops are literally defined as eschewing performance in favor of making it thinner and lighter. You make a processor that pulls half the power, the workstations will take twice the cores and the ultrabooks will slice off another 2mm of thickness and stay with dual cores. Zen did not change this dynamic.
Yes, Zen2 is a good product, this is not a Zen2 chip, nor is it really notably higher core count or anything else. It's a replacement for A8 piledrivers.
MacBook Pro has been shipping Quad Core SandyBridge since Early 2011. Along with many others in the PC world.
There are Chinese laptops like the Chuwui Lapbook Pro that get you a 1080p IPS screen, a quad-core Gemini Lake, and 8G of RAM for $320. I'd rather do that and be able to run standard x86 software at semi-reasonable speed than to mess with a chromebook. (I can see the draw for a momputer that you don't want to mess with though)
I'd love something in the 7nm or 10nm class, of course. If Dali was on Zen2 on 7nm it would be fantastic. It's just not possible yet in this price range. AMD is still launching 14nm in this segment, not even Zen+. Next-gen Atom (Skyhawk Lake) is going to be on Intel 14nm as well.
I'm curious how Dali/Barred Kestrel does on the extreme battery life/chromebook thing though. Raven Ridge (and the Zen+ successor, Picasso) did not have great idle power and this hurt it there. If they could get the idle power down, it would be a good alternative to Gemini Lake.
One of the fun things about ARM is that you get to play with asymmetric multicore machines that don't exist anywhere else in the desktop space. At least for now.
For me, the worst flaw of Chromebooks is the keyboard and the lack of proper Control, Super and Meta keys.
How so? They have a normal-enough ctrl and alt, and Chrome OS lets you remap the "search" key to control (<3).